The main reason is the fear of these countries will be the volatility and uncertainty of digital currency. In addition, as quoted from bitcoinbans.com, another reason is the fear if the digital currency is used as financing of terrorism.
A number of countries such as China are also reasoned, banning other digital currencies because it will issue its own currency.
A country that forbids bitcoin and its reasons
1. Nigeria, since 17 January 2017.
2. China, since January 8, 2017. Reason: will issue its own digital currency
3. Colombia, since 31 December 2016. Reason: worry of cryptocurrency fraud
4. Taiwan, since November 3, 2015. Reason: bitcoin hacking
5. Ecuador, since March 24, 2015. Reason: will issue its own currency
6. Bangladesh, since 22 September 2014. Reason: avoid money laundering
7. Kyrgyzstan, since August 4, 2014
8. Bolivia, since 19 June 2014
9. Vietnam, since February 28, 2014. Reason: can be used for crime and high risk to investors
10. Russia, since February 9, 2014. Reason: bitcoin is used for illegal activities
11. Thailand, since July 30, 2013. Bitcoin is not a currency
12. Morocco, since November 2017
13. South Korea, since December 13, 2017. Reason: to control its finances
14. Singapore, since 29 September 2017. Reason: arising constraints between financial companies
Nepal, since 2017
16. Indonesia, the ban applies 2018. Reason: high-risk natural bubble
17. Israel, starting 2018.